Application of the presentation-assimilation-discussion class in oral pathology teaching.

OBJECTIVES: The presentation-assimilation-discussion (PAD) class is a novel teaching method in which half the class time is allocated for the instructor's presentation and the other half for student's assimilation and discussion. This study evaluates and compares the teaching outcomes of the PAD class and traditional lecture-based method in oral pathology courses in School of Stomatology, Kunming Medical University. MATERIALS AND METHODS: The experimental and control groups included 88 undergraduates from Class 2017 and 72 undergraduates from Class 2016, respectively. The PAD method was applied on the experimental group in 2019, whereas the traditional lecture-based method was applied on the control group in 2018. The two groups' teaching outcomes were compared using final theory tests, biopsy diagnostic tests, and questionnaires. The Mann-Whitney U-test and independent-sample t-test were adopted for statistical analysis. RESULTS: In five multiple-choice questions examining the same knowledge point from final theory tests, the distribution of the final scores showed a statistically significant difference between the two groups (p < 0.05). In the biopsy diagnostic tests, the experimental group scored higher than the control group (p < 0.05). In the questionnaires, there was no statistically significant difference for the "enhancing knowledge mastery" item (p > 0.05). However, the experimental group showed significant superiority in the remaining nine items (p < 0.05). [Correction added on August 30, 2021, after first online publication: The data value p was corrected in the last sentence of result section.] CONCLUSIONS: Compared with the traditional lecture-based teaching, the PAD class stimulated a passion for learning among students and results in improved teaching outcomes. Therefore, the application of PAD class in oral pathology teaching should be recommended.

[Estrogen protects the dopaminergic neurons in substantia nigra against damage induced by 6-hydroxydopamine].

Substantial evidence strongly implies that sensory gating P50 (also called P50 auditory evoked potential, P50) and dopaminergic neurotransmitters are related. In animal experiment, P50 can be recorded in an awake and quiet state with freedom of movement. Until now there is lack of animal experimental data on the supportive effect of estrogen on function of dopaminergic neurons in substantia nigra (SN) in physiological state. In the present study, female Sprague-Dawley (SD) rats were used as subjects. The animals were divided randomly into four groups: (1) control group (normal animals); (2) Parkinson's disease (PD) model group: the right SN was lesioned with 6-hydroxydopamine (6-OHDA); (3) PD model with bilateral ovariectomized group (OVX-PD): bilateral ovariectomy was performed before administration with 6-OHDA; (4) estrogen + PD model with bilateral ovariectomized group (OVX-E(2)-PD): physiological dose of estrogen was given to the bilateral ovariectomy animals before administration with 6-OHDA. P50 induced by two brief acoustic stimuli were recorded in the right SN and the number of TH(+) dopaminergic neurons in the SN stained by immunohistochemistry was calculated after the determination of P50. The results showed that in the PD model group, the testing/conditioning (T/C) ratio of P50 decreased by 40.60% and the number of TH(+) cells in the right SN decreased by 64.74% as compared with that in the control group (P<0.01); In the OVX-PD group, the T/C ratio of P50 decreased by 45.88% and the number of TH(+) cells was reduced by 57.26% as compared with that in the PD group (P<0.01). Administration with 6-OHDA into the SN pars compacta of ovariectomized rats caused more decrease in the number of TH(+) cells as well as more damage to the function of sensory gating in SN. While in OVX-E(2)-PD group, intramuscular injection with estrogen at physiological dose 3 d before 6-OHDA administration decreased the degree of damage to the SN functionally and morphologically, and its degree of injury corresponded to PD group. These results indicate that the mechanism of protection of dopaminergic neurons in the SN provided by physiological level of estrogen is by promoting the resistibility of the neurons to harmful stimulation. If the gonads are resected resulting in a lack of estrogen, the degree of injury to the function and morphology of dopaminergic neurons in SN induced by 6-OHDA increases. Replacement of estrogen at physiological level on time is necessary. Sensory gating P50 in SN may reflect dynamically the protection of estrogen against dopaminergic neurons depletion in vivo.

[The morphological study of bone-implant interfaces in vivo].

OBJECTIVE: To evaluate the bone-implant interfaces of two kinds of implants with different surfaces in different time in vivo. METHODS: CDIC and ITI-TPS solid-screw cylinder pure titanium implants were selected and implanted in the regions of posterior molars of rhesus monkeys. 1 month, 2 months, 3 months and 1 year after surgery, the bone-implant interfaces were evaluated respectively through oral examination, X-ray inspection, light microscope and scanning electron microscope (SEM) observation. RESULTS: None of the implants was loose. Soft tissue around implants appeared no inflammation. There were no apparent transparent shadow around the implants interfaces in X-ray photos except little angle-shaped absorption was showed in neck region of CDIC implants of one-month. New bone was observed around implants of one-month through light microscope and SEM. More bone growing around ITI implants were seen than that around CDIC implants except the interfaces of one-year. CONCLUSION: The osseointegration of ITI implants are better than that of CDIC implants during three months after implanting without loading. The bone formation at the interfaces of ITI and CDIC implants has no significant difference after one year without loading.

[Expression and clinical significance of Fas-FasL of pleomorphic adenoma and adenoid cystic carcinoma in parotid gland].

OBJECTIVE: To determine the expression and clinical significance of Fas and FasL in cases of occurrence and development of pleomorphic adenoma and adenoid cystic carcinoma(ACC) in parotid gland. METHODS: Using Immunohistochemistry techniques and quantitative analysis under computerized system, we investigated Fas-FasL expression in 21 cases of normal parotid gland, 35 cases of pleomorphic adenoma in parotid gland and 32 cases of ACC in parotid gland. RESULTS: All cases of ACC of parotid gland showed Fas and FasL negative expression, no correlation was found between the expression of Fas-FasL and the histological type and the pathological grades of ACC. Although both normal parotid gland and pleomorphic adenoma of parotid gland had distinct expression of Fas and FasL, the positive expression of Fas FasL in pleomorphic adenoma of parotid gland cases were both significantly lowered (P<0.01) than that in normal parotid gland. CONCLUSION: Expression of Fas-FasL and Fas FasL mediated cell apoptosis disturbance had significant correlations with the occurrence and malignant development of pleomorphic adenoma and ACC in parotid gland.